Diagnostic trouble code
P1446 — Battery Module Individual Voltage Input Deviation (Honda IMA)
What it means in plain English
Your Honda IMA modules have drifted too far apart in voltage to work as one pack.
A hybrid pack only works when its modules stay close together in voltage. P1446 is set when the deviation between them exceeds what the battery computer will accept. It is the imbalance code rather than the wear code — the pack can still have reasonable total capacity while individual modules pull in different directions. Imbalance and deterioration usually arrive together on an older IMA pack, which is why P1446 and P1570 are so often stored side by side.
Which Toyota and Lexus models this applies to
Honda Integrated Motor Assist hybrids — Civic Hybrid, Insight, Accord Hybrid and CR-Z.
Possible causes
Plural on purpose. Any of these can produce this result — which is exactly why a code is not a diagnosis.
- Uneven module ageing, accelerated by heat on one side of the pack.
- A weak module that charges and discharges faster than its neighbours.
- Extended periods parked, which let the imbalance grow unchecked.
- Cooling airflow restricted on part of the pack, ageing those modules faster.
- Connection resistance at a bus bar making one module look worse than it is.
- A battery condition monitor fault producing false deviation readings.
What a professional diagnostic process should check
- 1Module-level voltages taken at rest and again under load — imbalance often only shows under load.
- 2Internal resistance per module, to separate a weak module from a poor connection.
- 3Inspect bus bars and terminals for corrosion and torque.
- 4Confirm the cooling fan runs and airflow reaches the whole pack, not just the intake end.
- 5Check whether the pack has been opened or partially repaired before.
- 6Verify 12V system health, which affects how the IMA system behaves.
What you can safely do now
- Ask for the module-by-module spread in writing — that number decides whether a repair is worth doing.
- Check the cabin-side intake for the battery cooling fan and keep it clear.
- Check your model year against Honda's IMA warranty extensions.
- Drive it regularly rather than letting it sit — sitting makes imbalance worse.
What not to do
- Don't have the pack "balanced" as a standalone service and expect it to hold if the modules are genuinely worn. Balancing an aged pack is temporary.
- Don't clear the code before diagnosis.
- Don't assume imbalance means the whole pack is finished — sometimes it genuinely is two modules.
When towing or urgent service is appropriate
Not normally a tow. The car drives on the engine with a failing IMA pack. Tow it if the engine won't start or if you have charging-system warnings alongside this code.
Not sure which category you're in? Call 623-323-0737 and describe what the car is doing. That call is free and it might save you a tow — or a much bigger repair.
Do not replace parts based on a code alone
Do not replace parts based on a code alone. A diagnostic trouble code tells you which circuit or system reported a problem — it does not identify which component failed. The same code can be set by several different faults, and clearing it without a diagnosis just hides the evidence. This page is educational; your vehicle needs its own inspection before any repair decision.
P1446 — common questions
What's the difference between P1446 and P1570?
Will reconditioning fix P1446?
Get P1446 diagnosed properly
Tell us the code, the year and model, and what the car is doing. We'll tell you what we'd check — and we won't quote a repair from a code.
Not sure what your hybrid needs? We'll work it out with you.
We come to you, test the pack, the 12V and the cooling, and you get a written quote before anything is decided. No obligation.